Brush-hair seal with a front plate and a bearing plate

ABSTRACT

A brush seal for sealing a rotor against a housing. The brush seal includes a front panel and a supporting plate attached to the housing wherein a number of bristles are disposed between the front panel and supporting plate. A seal housing that defines a fit surface is formed by cold joining the front panel and supporting plate. The front panel or the supporting plate include a beaded lip for firmly joining the front panel to the supporting plate.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention is directed to a brush seal having a front panel or plateand a supporting or bearing plate.

2. Description of the Prior Art

Many different brush seals are known that, for example, are utilized ingas turbines in order to seal the interspace, which is between a housingand a rotor rotating at a comparatively high speed, against leakage.Given such seals, the ends of the bristles, which are combined to form adense bristle packet, project beyond an inside edge of the supportingplate and thus seal the interspace, which is to be kept optimally small,between the inside edge of the supporting plate and the rotor surface.When a high differential pressure is adjacent the seal, then thesupporting plate arranged at the low-pressure side supports the bristlesto prevent sagging toward the low-pressure side.

For manufacturing a brush seal essentially composed of a front panel, asupporting plate and a bristle packet are arranged therebetween, weldingmethods were previously utilized with which, in particular, the frontpanel and supporting plate, which form a seal housing, are welded to oneanother.

Given a brush seal disclosed by European Patent Application 0 453 315,for example, the front panel, the bristle packet and the supportingplate are connected with a weld that extends over the outercircumference of the brush seal. Since the outer circumferential surfaceis a fitting surface and must proceed planarly and perpendicularlyrelative to the two outer lateral surfaces of the front panel and of thesupporting plate for an exactly fitting arrangement of the brush sealwith reference to the housing and to the rotor, additional processingsteps, for example grinding, are necessary due to the weld. This leadsto higher manufacturing costs and longer throughput times duringmanufacture.

It also proves disadvantageous when using the welding processes that thecomparatively thin front panel and supporting plates frequently warp dueto non-uniform temperature distributions.

German Patent Document No. DE 39 07 614 Al discloses a brush seal havinga wire bundle held in a slotted tube, wherein the tube is held togetherby two supporting rings joined to form a housing by one or more clamplips that are attached to the one supporting ring and embrace the secondsupporting ring at the outside to produce a clamping force. Thepositioning of the clamp lips ensues with a curling or rolling process.The manufacture of the two supporting rings is not disclosed, nor is theprovision of a fit surface at the brush seal housing.

SUMMARY OF THE INVENTION

The invention is based on the object of creating a brush seal whose sealhousing can be simply manufactured in fabrication-oriented terms, i.e.with optimally few processing procedures.

This yields the advantage that the seal housing is manufactured withoutthe application of heat and no warping occurs as a consequence ofdifferent temperature distributions. The additional processing of theouter circumferential or fitting surface that is always required givenwelding is thus eliminated. The front panel and supporting plate arecomposed of deep-drawn sheet metal members that are manufactured withexact fit, so that no further processing steps are required at the fitseat.

A free end of the front panel or of the supporting plate is fashioned asa beaded lip. The free end thereby lies at a rectangular sectionrelative to the main propagation plane of the front panel or supportingplate that is inwardly angled off upon respective formation of anoutside curved edge with an outside radius R. The beaded lip therebyembraces the outside curved edge of the respectively other plate to suchan extent that a rigid and reliable frictional connection of the twoplates exists.

The beaded lip includes a thickness s which is reduced compared to thethickness S of the material of the front panel or supporting plate. Thethickness s, just like the length l of the beaded lip, is to be selecteddependent on the thickness of the material as well as on the shape ofthe plates, the structural height of the brushes, the bending radii,etc.

Preferably, the thickness s of the beaded lip amounts to approximately{fraction (2/3+L )} of the thickness S of the material of the frontpanel or supporting plate.

It is also advantageous that the arc is circular and the correspondingbending radius r is equal to 1.1 through 1.5 times the thickness S ofthe material of the front panel or supporting plate.

Preferably, the bending radius r is equal to the outside radius R at theoutside edge of the front panel or supporting plate.

The front panel and supporting plate can be composed of sheet steel,wherein special steels can also be utilized.

The bristles or the bristle packet are preferably clamped non-positivelyby the cold joining of the front panel and supporting plate. As a resultthereof, the bristles not only seal but a co-rotation of the bristlepacket given extreme brushing of the rotor is also avoided. In order toenhance the coefficient of friction, a C-tube serving for the acceptanceof the bristles or the inside surfaces of the front panel and supportingplate can, for example, be roughened, knurled or can be provided withnotches.

DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic cross sectional view of an exemplary embodimentof the inventive brush seal.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 shows a brush seal referenced 1 overall that is clamped in ahousing 2 through which a rotor (not shown) extends. The brush seal 1includes a housing essentially constructed of a pair of memberscomprising an annular front panel 3 and an annular supporting plate 4and also includes a multitude of tightly packed bristles 5 in a slottedC-tube 11 which is firmly clamped between the front panel 3 and thesupporting plate 4 at a clamping location 6.

As illustrated, the front panel 3 has a lateral surface 10 and acylindrical flange with an outer cylindrical, circumferential surface 9.The supporting plate 4 has a cylindrical flange connected to a lateralsurface 10 by an outside curved edge 8 with a radius of curvature R. Theflange of the supporting plate 4 is received in the flange of the frontpanel 4 with the slotted tube 11 containing the bristles 5 clampedtherebetween.

Given a differential pressure adjacent the brush seal 1, the front panel3 is arranged at the high-pressure side and the supporting plate 4 isarranged at the low-pressure side. The bristles 5 clamped at one sideextend between the front panel 3 and the supporting plate 4 and havetheir free ends remote from the clamping location 6 extending beyondinside edges of the front panel 3 and of the supporting plate 4. Theends of the bristles 5 touch the rotor surface and thus seal an annularinterspace between the supporting plate 4 and the rotor.

In the present exemplary embodiment, the front panel 3 and thesupporting plate 4 are a sheet material of the same thickness S. Abeaded lip 7 that has a smaller thickness s is fashioned at a free endof the flange of the front panel 3 and adjoins the outer circumferentialsurface 9. The thickness s amounts to approximately {fraction (2/3+L )}of the thickness S of the sheet material. To form the beaded lip 7, thematerial is removed from the outwardly directed surface of the flange ofthe front panel 3.

The beaded lip 7 does not completely embrace the outside curved edge 8of the supporting plate 4 but only embraces the curved edge in adeformation angle a in a range of approximately 60° to 90°. A rigid andfirm, non-positive connection between the front panel 3 and supportingplate 4 is created with this deformation angle, and this simultaneouslyassures that the bristles 5 are also firmly clamped between the frontpanel 3 and the supporting plate 4. The bending radius r of the lip 7 isequal to the outside radius R of the outside curved edge 8, so that thebeaded lip 7 conforms to the contour of the supporting plate 4 or theoutside curved edge 8 thereof.

This outer circumferential surface 9 adjoining the beaded lip 7 is a fitsurface that must be cylindrical for an exactly fitted attachment of thebrush seal 1 between the housing 2 and the rotor, and the surface 9 mustgenerally proceed perpendicular to the two outer lateral surfaces 10 ofthe front panel 3 and supporting plate 4. The thickness s, the radius rand the length l of the beaded lip 7 are therefor to be selected suchthat the aforementioned demands made of the fit surface 9 are met afterthe cold joining or working.

Although modifications and changes may be suggested by those skilled inthe art, it is the intention of the inventors to embody within thepatent warranted hereon all changes and modifications as reasonably andproperly come within the scope of their contribution to the art.

What is claimed is:
 1. A brush seal for sealing a rotor against ahousing comprising a pair of members including a front panel and asupporting plate, each of said members being an annular member of asheet material with a cylindrical flange with an outer cylindricalcircumferential surface, one of the pair of members having the outercylindrical circumferential surface being connected to the lateralsurface by an outside curved edge with a radius of curvature R, theouter cylindrical circumferential surface of the other member of saidpair of members forming a fitting surface for engaging in a cylindricalsurface of the housing, the cylindrical flange of said other memberterminating in a beaded lip having a thickness less than the thicknessof the sheet material, said members being joined together with thecylindrical flange of the one member being received within thecylindrical flange of the other member and with a plurality of bristlesdisposed between the pair of members with the bristles having a free endextending inwardly beyond an inner edge of each of said members, saidpair of members being joined together by the beaded lip extending in acircular arc of 60° to 90° and embracing the outside curved edge of saidone member.
 2. A brush seal according to claim 1, wherein the thicknessof the beaded lip amounts to approximately {fraction (2/3+L )} of thethickness of the sheet material of the other member.
 3. A brush sealaccording to claim 2, wherein the circular arc has a radius of curvatureequal to 1.1 to 1.5 times the thickness of the sheet material of saidpair of members.
 4. A brush seal according to claim 3, wherein theradius of curvature of the bead is equal to the radius R of said outsidecurved edge of the one member.
 5. A brush seal according to claim 1,wherein the cylindrical circumferential surface of the other memberextends perpendicular to the outer lateral surfaces of the pair ofmembers.
 6. A brush seal according to claim 1, wherein the pair ofmembers are composed of deep-drawn steel sheet.
 7. A brush sealaccording to claim 1, wherein the arc of the beaded lip has a radius ofcurvature r equal to 1.1 to 1.5 times the thickness of the sheetmaterial of said members.
 8. A brush seal according to claim 7, whereinthe radius r is equal to the radius R of the outside curved edge of saidone member.